1. Field of the Invention
The present invention generally relates to the field of semiconductor wafer testing and, more particularly, to a non-contact method for measuring epitaxial dopant concentration profiles in such wafers.
2. Description of the Prior Art
Currently, Metal Oxide Semiconductor (MOS) Pulsed Capacitance-Voltage (C-V) doping concentration profiles are used to control epitaxial silicon process sectors. The MOS method is described, for example, by E.H. Nicollian and J.R. Brews in MOS Physics and Technology, John Wiley and Sons (1982), at pages 383-406, and provides repeatable, accurate profiles. However, MOS sample preparation is expensive, time consuming and destructive. Labor and equipment is need ed for depositing front-side aluminum dots and back-side blanket aluminum. Several days of turn around time usually result from wafer queuing and processing for the aluminum steps. Also, the destructive nature of the sample preparation forces the undesirable use of expensive monitor wafers which are not completely representative of product wafers.